This invention relates generally to wireless communications circuitry, and more particularly, to ways for testing the performance the wireless communications circuitry.
Wireless electronic devices typically contain wireless communications circuitry that includes radio-frequency power amplifiers. Radio-frequency power amplifiers are used to amplify radio-frequency signals for wireless transmission in a desired radio-frequency channel (i.e., a radio channel). The radio-frequency performance of a device under test (DUT) can be measured using a test station. A test station typically includes a test host, a test unit that is connected to the test host, and a test cell that is connected to the test unit via a radio-frequency cable. The DUT is placed within the test cell prior to testing. Radio-frequency test signals are conveyed between the DUT and the test unit during test operations.
Conventional techniques for testing the power amplifiers involve configuring the power amplifiers to transmit radio-frequency signals at maximum output power levels across an entire radio channel. For example, consider a scenario in which a wireless DUT having a cellular telephone transceiver that is configured to operate using the Universal Mobile Telecommunications System (UMTS) network communications protocol is tested using a test station. The test host may direct the DUT to transmit radio-frequency signals at maximum output power across an entire 5 MHz channel currently being tested.
Transmitting at maximum power across the entire radio channel places the power amplifiers under an elevated stress level (i.e., transmitting at maximum power across the entire channel maximizes adjacent channel leakage) that is desirable during testing to validate design specifications or to help magnify the effects of manufacturing defects/variations (if present) associated with the radio-frequency power amplifiers in the DUT. The test unit receives the signals transmitted from the DUT and performs desired radio-frequency measurements on the received signals. The test host is used to determine whether or not the power amplifiers on the DUT satisfy performance criteria based on the gathered measurement data.
Electronic devices that communicate using newer wireless network communications technologies such as the Long Term Evolution LTE) network communications protocol have been developed. The LTE network communications protocol, however, does not allow radio-frequency signals to be transmitted at maximum output power levels across an entire channel. If conventional test methods are used, the DUT would transmit radio-frequency signals at a fixed output power level that is less than the maximum output power level across the entire channel. Testing the DUT in this way may be undesirable, because the power amplifiers are not placed under sufficiently elevated stress levels (i.e., testing the DUT while the power amplifier is transmitting at an output power level that is less than the maximum output power level does not maximize adjacent channel leakage, error vector magnitude, spurious emission, and current consumption).
It would therefore be desirable to be able to provide improved ways for testing power amplifier performance.